Self feeders are ok up to about 100 lbs or so in my opinion, after that, the pig needs to be hand fed in my opinion. Just like with cattle, if feed is left in front of them all the time they dont eat as much. With any animal the ideal situation is to evaluate the animal and try to decided what weight they are going to be ideal at, and then try and feed them in order to have them at that weight for the fair.
For pigs, I would say the average gain for most pigs to have them proper for the fair is going to be about 2lbs a day, but remember I said that is average. For most feeds with pigs you get about a 2:1 gain ratio, so for every 2 lbs they eat they will gain about a lb. The program I have had the best luck on is leaving them on a self feeder until about 100 lbs, then I feed about 6 lbs a day until they are about 175, then I start to weigh them once a week, decide what they rate of gain is on the feed, decide what I want them to weigh at the fair, then I adjust my feeding to try to end up at that weight at the fair.
Remember with pigs you have to work them. They need to be excersised daily. If you dont practice driving them at home, you will never get them drove in the show ring. Once the pig is settled into your pens after a few weeks dont be afraid to let them out of the pen to drive them and excercise them, a pig will almost always come back to the feed trough.
As far as what outspoken said earlier warning about the loans, I dont know the situation that caused him to not have the animals he purchased after 5 yrs. But I do know that I and most other breeders, if we spend $5,000 on breeding stock, then we expect that animal to still be around and producing in 5 yrs. Now there are always freak accidents and unexpected circumstances, but generally if you are dilligent in your shopping and make sure you buy good animals, then one heifer will generally more than pay back the loan like that it took to buy her. And another thing he eluded to in that post, and Jody this isnt an attack just trying to educate the youngsters here. But dont think that just because it cost a lot it is qualty, in that post he said something about it was obvious he got quality stock because he spent $5k, but let me tell you, I have seen a lot of $5k and $10k animals out there that were complete junk, and I can show you plenty of $1500 animals that were a lot higher quality than them, dont let the fact that they are priced higher let you believe that they are higher quality.